Once upon a time, lived a king who was short tempered. One morning, king was going out to see his beloved horse. At same time, a monk came here to beg for alms. Because of sudden interruption, king became angry. In anger, he picked up waste from stable and put it in monk's begging bowl. Monk didn't said anything and left. Few days later, raja set out on a city tour. On his way he saw a big pile of garbage outside a hut. When king went inside, he saw same monk sitting there. King asked, "Why there is so much dirt outside your house?"Monk replied, "This is the same waste, you gave me that day."King questioned, "That day I had put a little garbage in your begging bowl but there is a big pile of garbage outside your house. how is that possible?"Monk replied, "When we give something good or bad to someone, it keeps increasing day by day and accordingly get good or bad fruits of his doing."Hearing this king trembled in fear. King understood his mistake and apologized to monk for his wrong doing. He asked, "Please tell me how can I atone for this mistake?"Monk said, "There is one thing you can do. you should pretend to do something in which people will think evil for you, curse you and this will reduce your sin."King understood. Next day, king sat at cross roads of city with a bottle of wine and pretend to drink and acted like drunk. When people saw him in such condition, everyone started to condemn him and he stayed same way from morning to evening. Next day, king again went to monk's hut and there he saw that pile of garbage outside was reduced. King was surprised and asked monk, "How come this pile is reduced?"Monk replied, "People who have cursed you, done wrong to you yesterday without knowing truth, your sin has been divided equally among them and due to that pile of filth had also reduced." When we do something bad to someone then that evil comes to us again, after being many fold. So never do anything bad to anyone. 
Also, it should be kept in mind that one should no do evil or curse anyone one without thinking or knowing truth because by doing this we also became a partaker of his sin. 